Technical Field
The present invention relates to a compact for producing a sintered alloy containing hard particles which are preferable for improving mechanical strength and wear resistance of a sintered alloy, a wear-resistant iron-based sintered alloy obtained by sintering the compact, and a method for producing the same.
Background Art
Conventionally, a sintered alloy including an iron-based substrate is used for a valve sheet or the like in some cases. Hard particles can be added to a sintered alloy to further improve wear resistance. In general, when hard particles are added, a hard powder including hard particles is mixed with a powder having a composition of a low-alloy steel or stainless steel. The obtained powder mixture is formed into a compact for producing a sintered alloy by powder compacting. Then, the compact for producing a sintered alloy is sintered to obtain a sintered alloy.
As a method for producing such sintered alloy, a method for producing a wear-resistant iron-based sintered alloy, which includes: forming a compact for producing a sintered alloy from a powder mixture containing a hard powder, a graphite powder, and an iron-based powder by powder compacting; and sintering the compact for producing a sintered alloy while diffusing C in the graphite powder of the compact for producing a sintered alloy in hard particles that constitute the hard powder has been suggested (see, e.g., Patent Document 1). The hard particles that constitute a hard powder contain 20% to 60% by mass of Mo and 3% to 15% by mass of Mn, with the balance made up of incidental impurities and Fe. The hard powder and the graphite powder contained in the powder mixture account for 15% to 60% by mass and 0.2 to 2% by mass of the total amount of the hard powder, the graphite powder, and the iron-based powder, respectively. According to the above production method, the amount of carbon contained in hard particles is limited, thereby making it possible to improve wear resistance of a sintered alloy obtained by sintering a compact while increasing formability of the compact before sintering.